Colored glass plate and method for its production

ABSTRACT

To provide a colored glass plate which, despite containing substantially no expensive cerium, simultaneously satisfies low solar transmittance, high visible light transmittance and low UV transmittance, while transmitted light has a green color tone. The colored glass plate comprises, as represented by mass percentage based on oxides, SiO 2 : from 65 to 75%, Al 2 O 3 : from 0 to 6%, MgO: from 2 to 6%, CaO: from 5 to 15%, total iron calculated as Fe 2 O 3 : from 0.3 to 1.2%, total titanium calculated as TiO 2 : from 0.2 to 1.1%, and total vanadium calculated as V 2 O 5 : from 0.02 to 0.3%, and contains substantially no cerium, cobalt, chromium or manganese.

TECHNICAL FIELD

The present invention relates to a colored glass plate whichsimultaneously satisfies low solar transmittance, high visible lighttransmittance and low UV transmittance, while transmitted light has agreen color tone, and a method for its production.

BACKGROUND ART

As a glass plate for automobiles, a colored glass plate (e.g. aheat-absorbing glass plate or a UV-absorbing glass plate) is known,which contains a colorant component whereby transmitted light has agreen or blue color tone.

For such a colored glass plate, the solar transmittance is required tohe low (e.g. the value, as calculated in a thickness of 4 mm, of solartransmittance (hereinafter referred to also as Te) stipulated in JISR3106 (1998) is required to be at most 55%). Further, the visible lighttransmittance is required to be high (e.g. the value, as calculated in athickness of 4 mm, of visible light transmittance (illuminant A, 2degrees field of vision) (hereinafter referred to also as Tv) stipulatedin JIS R3106 (1998) is required to be at least 70%). Further, theUV-transmittance is required to be low (e.g. the value, as calculated ina thickness of 4 mm, of UV-transmittance (hereinafter referred to alsoas Tuv) stipulated in ISO-9050 is required to be at most 12%).

Further, as such a colored glass plate, a glass plate tends to bepreferred such that when a passenger watches the scenery through theglass plate, the color tone of the transmitted light has a green colortone being a more natural color tone (e.g. the dominant wavelength(hereinafter referred to as also as Dw) of transmitted light stipulatedin JIS Z8701 (1982) is from 540 to 570 nm).

Further, for such a colored glass plate, it is desired that types ofcolorant components be reduced as far as possible and that unit pricesof raw materials for colorant components be low, from the viewpoint ofcosts and with a view to preventing inclusion of impurities at the timeof changing the base material (i.e. changing the product type) in themelting furnace to be used for the production of glass.

As colored glass plates whereby transmitted light has a green colortone, for example, the following (1) to (3) have been proposed.

(1) Green glass comprising, per 100 parts by mass of a soda lime silicaglass matrix composition,

total iron calculated as Fe₂O₃: from 0.5 to 2.0 parts by mass,

total titanium calculated as TiO₂: more than 1.0 part by mass and atmost 3.0 parts by mass,

CoO: from 0.003 to 0.02 part by mass,

Se: from 0 to 0.0008 part by mass,

total chromium calculated as Cr₂O₃: from 0 to 0.05 part by mass,

total vanadium calculated as V₂O₅: from 0 to 0.5 part by mass, and

total cerium calculated as CeO₂: from 0 to 0.5 part by mass,

wherein the mass proportion of bivalent iron calculated as Fe₂O₃ in thetotal iron calculated as Fe₂O₃ is from 31 to 50%.

(2) UV-absorbing green glass made substantially of soda lime silicaglass and comprising, as represented by mass percentage based on oxides,

total iron calculated as Fe₂O₃: from 0.45 to 0.491%,

total cerium calculated as CeO₂: from 1.09 to 1.2%,

total titanium calculated as TiO₂: from 0.3 to 0.39%, and

CoO: from 0 to 0.0003%,

wherein the mass proportion of bivalent iron calculated as Fe₂O₃ in thetotal iron calculated as Fe₂O₃ is from 30.5 to 32.0%.

(3) UV-absorbing green glass made substantially of soda lime silicaglass and comprising, as represented by mass percentage based on oxides,

total iron calculated as Fe₂O₃: from 0.52 to 0.63%,

total cerium calculated as CeO₂: from 0.9 to 2%,

total titanium calculated as TiO₂: from 0.2 to 0.6%, and

CoO: from 0 to 0.002%,

wherein the mass proportion of bivalent iron calculated as Fe₂O₃ in thetotal iron calculated as Fe₂O₃ is from 31 to 38%.

However, the green glass of (1) has a problem such that since thecontent of CoO is large, Tv is low, and Dw is also low (i.e. transmittedlight is bluish green). On the other hand, in the case of theUV-absorbing green glasses of (2) and (3), the content of CoO is small,and the content of total cerium calculated as CeO₂ is large, whereby Tvis high, and Tuv is sufficiently low.

However, recently, the prices for cerium raw materials have gone up, andaccordingly the cost for green glass having a large content of totalcerium calculated as CeO₂ has gone up. Therefore, a colored glass plateis desired which contains substantially no cerium and whichsimultaneously satisfies low solar transmittance, high visible lighttransmittance and low UV transmittance, while transmitted light has agreen color tone.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent No. 3,256,243

Patent Document 2: Japanese Patent No. 3,900,550

Patent Document 3: Japanese Patent No. 3,190,965

DISCLOSURE OF INVENTION Technical Problem

The present invention is to provide a colored glass plate which, despitecontaining substantially no expensive cerium, simultaneously satisfieslow solar transmittance, high visible light transmittance and low UVtransmittance, while transmitted light has a green color tone.

Solution to Problem

The colored glass plate of the present invention is characterized bycomprising, as represented by mass percentage based on oxides,

SiO₂: from 65 to 75%,

Al₂O₃: from 0 to 6%,

MgO: from 2 to 6%,

CaO: from 5 to 15%,

total iron calculated as Fe₂O₃: from 0.3 to 1.2%,

total titanium calculated as TiO₂: from 0.2 to 1.1%, and

total vanadium calculated as V₂O₅: from 0.02 to 0.3%,

and containing substantially no cerium, cobalt, chromium or manganese.

The colored glass plate of the present invention preferably furthercontains, as represented by mass percentage based on oxide, from 5 to18% of Na₂O.

The colored glass plate of the present invention preferably has

a solar transmittance (Te) as stipulated in JIS R3106 (1998) of at most55% as a value calculated in a thickness of 4 mm,

a visible light transmittance (Tv) (illuminant A, 2 degrees field ofvision) as stipulated in JIS R3106 (1998) of at least 70% as a valuecalculated in a thickness of 4 mm,

an UV transmittance (Tuv) as stipulated in ISO-9050 of at most 12% as avalue calculated in a thickness of 4 mm, and

a dominant wavelength (Dw) of transmitted light as stipulated in JISZ8701 (1982) of from 540 to 570 nm.

The method for producing a colored glass plate of the present invention,comprises melting glass raw materials, followed by forming to obtain acolored glass plate comprising, as compositional components of the glassplate after the forming and as represented by mass percentage based onoxides,

SiO₂: from 65 to 75%,

Al₂O₃: from 0 to 6%,

MgO: from 2 to 6%,

CaO: from 5 to 15%,

total iron calculated as Fe₂O₃: from 0.3 to 1.2%,

total titanium calculated as TiO₂: from 0.2 to 1.1%, and

total vanadium calculated as V₂O₅: from 0.02 to 0.3%, and containingsubstantially no cerium, cobalt, chromium or manganese.

In the method for producing a colored glass plate of the presentinvention, it is preferred that the glass plate further contains, as itscompositional component and as represented by mass percentage based onoxide, from 5 to 18% of Na₂O.

In the method for producing a colored glass plate of the presentinvention, it is preferred to obtain the colored glass plate which has

a solar transmittance (Te) as stipulated in JIS R3106 (1998) of at most55% as a value calculated in a thickness of 4 mm,

a visible light transmittance (Tv) (illuminant A, 2 degrees field ofvision) as stipulated in JIS R3106 (1998) of at least 70% as a valuecalculated in a thickness of 4 mm,

an UV transmittance (Tuv) as stipulated in ISO-9050 of at most 12% as avalue calculated in a thickness of 4 mm, and

a dominant wavelength (Dw) of transmitted light as stipulated in JISZ8701 (1982) of from 540 to 570 nm.

The above expression “to” to represent a numerical range, is used toinclude the numerical values given before and after the expression asthe lower limit value and the upper limit value, respectively, andhereinafter in this specification, the same expression “to” is used tohave the same meaning, unless otherwise specified.

Advantageous Effects of Invention

The colored glass plate of the present invention, despite containingsubstantially no expensive cerium, simultaneously satisfies low solartransmittance, high visible light transmittance and low UVtransmittance, while transmitted light has a green color tone.

DESCRIPTION OF EMBODIMENTS

The colored glass plate of the present invention is one containing SiO₂as the main component, and from the viewpoint of the cost of the glassplate, it is preferably one made of so-called soda lime silica glasswhich further contains Na₂O, CaO, etc.

The colored glass plate of the present invention has the followingcomposition (I). The colored glass plate of the present inventionpreferably has the following composition (II), more preferably has thefollowing composition (III), further preferably has the followingcomposition (IV).

(I) A composition comprising, as represented by mass percentage based onthe following oxides,

SiO₂: from 65 to 75%,

Al₂O₃: from 0 to 6%,

MgO: from 2 to 6%,

CaO: from 5 to 15%,

total iron calculated as Fe₂O₃: from 0.3 to 1.2%,

total titanium calculated as TiO₂: from 0.2 to 1.1%, and

total vanadium calculated as V₂O₅: from 0.02 to 0.3%,

and containing substantially no cerium, cobalt, chromium or manganese.

(II) A composition comprising, as represented by mass percentage basedon the following oxides,

SiO₂: from 65 to 75%,

Al₂O₃: from 0 to 6%,

MgO: from 2 to 6%,

CaO: from 5 to 15%,

Na₂O: from 5 to 18%,

total iron calculated as Fe₂O₃: from 0.3 to 1.2%,

total titanium calculated as TiO₂: from 0.2 to 1.1%, and

total vanadium calculated as V₂O₅: from 0.02 to 0.3%, and containingsubstantially no cerium, cobalt, chromium or manganese.

(III) A composition comprising, as represented by mass percentage basedon the following oxides,

SiO₂: from 68 to 73%,

Al₂O₃: from 0.5 to 3.5%,

MgO: from 2.5 to 5%,

CaO: from 6 to 11%,

Na₂O+K₂O: from 10 to 18%,

total iron calculated as Fe₂O₃: from 0.5 to 0.9%,

total titanium calculated as TiO₂: from 0.5 to 1.0%, and

total vanadium calculated as V₂O₅: from 0.05 to 0.20%, and containingsubstantially no cerium, cobalt, chromium or manganese.

(IV) A composition comprising, as represented by mass percentage basedon the following oxides,

SiO₂: from 70 to 72%,

Al₂O₃: from 1.5 to 2.0%,

MgO: from 3 to 4%,

CaO: from 7 to 9%,

Na₂O+K₂O: from 11 to 16%,

total iron calculated as Fe₂O3: from 0.6 to 0.7%,

total titanium calculated as TiO₂: from 0.7 to 0.9%, and

total vanadium calculated as V₂O₅: from 0.10 to 0.15%, and containingsubstantially no cerium, cobalt, chromium or manganese.

The colored glass plate of the present invention is characterized inthat Tuv is lowered by incorporating vanadium instead of cerium, Te islowered by incorporating iron, and Tv is made high while making Dw to befrom 540 to 570 nm as desired, by adjusting the content of total ironcalculated as Fe2O₃, the content of total titanium calculated as TiO₂and the content of total vanadium calculated as V₂O₅.

The content of total iron calculated as Fe₂O₃ is from 0.3 to 1.2%, asrepresented by mass percentage based on oxide. When the content of totaliron calculated as Fe₂O₃ is at least 0.3%, it is possible to lower Te.As content of total iron calculated as Fe₂O₃ increases, Te lowers, butTv also lowers. When the content of total iron calculated as Fe₂O₃ ismade to be at most 1.2%, it is possible to prevent lowering of Tv and tobring Tv to be at least 70% (as calculated in a thickness of 4 mm). Thecontent of total iron calculated as Fe₂O₃ is preferably from 0.5 to0.9%, more preferably from 0.6 to 0.7%, as represented by masspercentage based on oxide.

The content of total titanium calculated as TiO₂ is from 0.2 to 1.1%, asrepresented by mass percentage based on oxide. When the content of TiO₂is at least 0.2%, it is possible to adjust Dw to be at least 540 nm.Further, it is possible to lower Tuv. When the content of TiO₂ is atmost 1.1%, it is possible to adjust Dw to be at most 570 nm. Further, itis possible to make Tv to be high. The content of total titaniumcalculated as TiO₂ is preferably from 0.5 to 1.0%, more preferably from0.7 to 0.9%, as represented by mass percentage based on oxide.

The content of total vanadium calculated as V₂O₅ is from 0.02 to 0.3%,as represented by mass percentage based on oxide. When the content ofV₂O₅ is at least 0.02%, it is possible to lower Tuv. When the content ofV₂O₅ is at most 0.3%, it is possible to make Tv to be high. The contentof total vanadium calculated as V₂O₅ is preferably from 0.05 to 0.20%,more preferably from 0.10 to 0.15%, as represented by mass percentagebased on oxide.

The colored glass plate of the present invention contains substantiallyno cerium, cobalt, chromium or manganese which has, heretofore, beenused as a typical colorant component. Here, “contains substantially nocerium, cobalt, chromium or manganese” means that cerium, cobalt,chromium or manganese is not contained at all, or cerium, cobalt,chromium or manganese may be contained as impurities unavoidablyincluded during the production. When cerium, cobalt, chromium ormanganese is not contained substantially, Tv can be made high, it ispossible to prevent inclusion of impurities at the time of changing thebase material, and the cost for the colored glass plate can besuppressed. The content of such impurities may vary depending upon theglass raw material to be used, but in the case of a glass plate forautomobiles or buildings, it is preferably made to be less than 0.1%,more preferably less than 0.05%, further preferably less than 0.01%, asrepresented by mass percentage.

Here, “inclusion of impurities at the time of changing the basematerial” means the following.

During its production, glass may sometimes be switched to another glasstype having a different glass composition (i.e. change of the basematerial). The inclusion of impurities at the time of changing the basematerial means that at the time of switching to another glass type,components of the glass before switching are included into the glassafter switching. If inclusion of impurities such as cerium, cobalt,chromium, manganese, etc., takes place, after the switching, the colortone of the glass will be thereby substantially influenced.

SiO₂ is the main component of glass.

The content of SiO₂ is, as represented by mass percentage based onoxide, from 65 to 75%. When the content of SiO₂ is at least 65%, theweather resistance will be good. When the content of SiO₂ is at most75%, devitrification is less likely to take place. The content of SiO₂is, as represented by mass percentage based on oxide, preferably from 68to 73%, more preferably from 70 to 72%.

Al₂O₃ is a component to improve the weather resistance.

The content of Al₂O₃ is, as represented by mass percentage based onoxide, from 0 to 6%. When the content of Al₂O₃ is at most 6%, themelting properties will be good. The content of Al₂O₃ is, as representedby mass percentage based on oxide, preferably from 0.5 to 3.5%, morepreferably from 1.5 to 2.0%.

MgO is a component to accelerate melting of the glass raw material andto improve the weather resistance.

The content of Mg0 is, as represented by mass percentage based on oxide,from 2 to 6%. When the content of MgO is at least 2%, the meltingproperties and weather resistance will be good. When the content of MgOis at most 6%, devitrification is less likely to take place. The contentof MgO is, as represented by mass percentage based on oxide, preferablyfrom 2.5 to 5%, more preferably from 3 to 4%.

CaO is a component to accelerate melting of the glass raw material andto improve the weather resistance.

The content of CaO is, as represented by mass percentage based on oxide,from 5 to 15%. When the content of CaO is at least 5%, the meltingproperties and weather resistance will be good. When the content of CaOis at most 15%, devitrification is less likely to take place. Thecontent of CaO is, as represented by mass percentage based on oxide,preferably from 6 to 11%, more preferably from 7 to 9%.

The colored glass plate of the present invention may contain SrO inorder to accelerate melting of the glass raw material. The content ofSrO is, as represented by mass percentage based on oxide, preferablyfrom 0 to 5%, more preferably from 0 to 3%. When the content of SrO isat most 5%, the melting of the glass raw material can sufficiently beaccelerated.

The colored glass plate of the present invention may contain BaO inorder to accelerate melting of the glass raw material. The content ofBaO is, as represented by mass percentage based on oxide, preferablyfrom 0 to 5%, more preferably from 0 to 3%. When the content of BaO isat most 5%, the melting of the glass raw material can sufficiently beaccelerated.

The colored glass plate of the present invention preferably containsNa₂O and K₂O, or Na₂O, in order to accelerate melting of the glass rawmaterial. The total content of Na₂O and K₂O is, as represented by masspercentage based on oxides, preferably from 10 to 18%, more preferablyfrom 11 to 16%, further preferably from 12 to 14%. When the content ofNa₂O+K₂O is at least 10%, the melting properties will be good. When thecontent of Na₂O+K₂O is at most 18%, the weather resistance will be good.

The content of Na₂O is, as represented by mass percentage based onoxide, preferably from 5 to 18%, more preferably from 10 to 16%, furtherpreferably from 12 to 15%.

The content of K₂O is, as represented by mass percentage based on oxide,preferably from 0 to 5%, more preferably from 0.2 to 1%, furtherpreferably from 0.2 to 0.4%.

The colored glass plate of the present invention may contain SO₃ used asa lining agent. The content of SO₃ is, as represented by mass percentagebased on oxide, preferably from 0 to 1%, more preferably from 0.01 to0.5%, further preferably from 0.05 to 0.2%. When the content of SO₃ isat most 1%, the gas component of SO₂ is less likely to remain as gasbubbles in glass.

The colored glass plate of the present invention may contain SnO₂ usedas a fining agent. The content of SnO₂ is, as represented by masspercentage based on oxide, preferably from 0 to 0.5%, more preferablyfrom 0 to 0.3%, further preferably from 0 to 0.1%. When the content ofSnO₂ is at most 0.5%, volatilization of SnO₂ tends to be less, and it ispossible to suppress the cost to be low.

The specific gravity of the colored glass plate of the present inventionis preferably from 2.49 to 2.55, more preferably from 2.50 to 2.52. Bybringing the specific gravity of the colored glass plate of the presentinvention to be equal to usual soda lime silica glass, it is possible toimprove the efficiency for changing the composition (i.e. changing thebase material) at the time of the production.

The specific gravity of the colored glass plate of the present inventioncan be adjusted by adjusting the glass matrix composition. To adjust thespecific gravity to the above level, the mass ratio ofSiO₂/(MgO+CaO+SrO+BaO) is made to be preferably from 5.0 to 8.0, morepreferably from 5.5 to 6.5. Here, (MgO+CaO+Sr)+BaO) represents the totalcontent of MgO, CaO, SrO and BaO which are contained.

Te (as calculated in a thickness of 4 mm) of the colored glass plate ofthe present invention is at most 55%, preferably at most 53%, morepreferably at most 50%. To is a solar transmittance calculated bymeasuring the transmittance by a spectrophtotometer in accordance withJIS R3106 (1998) (hereinafter referred to simply as JIS R3106).

Tv (as calculated in a thickness of 4 mm) of the colored glass plate ofthe present invention is at least 70%, preferably at least 71.5%. Tv isa visible light transmittance calculated by measuring the transmittanceby a spectrophotometer in accordance with JIS R3106. As the coefficient,a value of standard illuminant A, 2 degrees field of vision is employed.

Tuv (as calculated in a thickness of 4 mm) of the colored glass plate ofthe present invention is at most 12%, preferably at most 10%. Tuv is aUV transmittance calculated by measuring the transmittance by aspectrophotometer in accordance with ISO-9050.

The dominant wavelength (Dw) of transmitted light through the coloredglass plate of the present invention is from 540 to 570 nm, preferablyfrom 550 to 560 nm, more preferably from 552 to 556 nm. When thedominant wavelength is within the above range, it is possible to obtaina colored glass plate whereby transmitted light has the desired greencolor tone. The dominant wavelength is one calculated by measuring thetransmittance by a spectrophotometer in accordance with JIS Z8701(1982). As the coefficient, a value of standard light C, 2 degrees fieldof vision is employed.

The colored glass plate of the present invention may be used for eithervehicles or buildings and is particularly useful as a windshield or doorglass for automobiles In a case where it is to be used as a window glassfor an automobile, as the case requires, it may be used in the form oflaminated glass having a plurality of glass plates laminated with aninterlayer, glass having flat glass processed to have a curved surface,or glass having tempering treatment applied. Otherwise, in a case whereit is to be used as double-layered glass for buildings, it may be usedin the form of double-layered glass composed of two colored glass platesof the present invention, or double-layered glass composed of a coloredglass plate of the present invention and another glass plate.

The colored glass plate of the present invention may be produced, forexample, via the following sequential steps (i) to (iv) and, as the caserequires, further via a step (V).

(i) In order to attain a desired glass composition, glass matrixcomposition raw materials such as silica sand, etc., colorant componentraw materials such as an iron source, a titanium source, a vanadiumsource, etc., an oxidizing agent, a reducing agent, a fining agent,etc., are suitably mixed to prepare a glass raw material.

(ii) The glass raw material is continuously supplied to a meltingfurnace, heated to from about 1,400 to 1,600° C. (e.g. about 1,500° C.)by heavy oil, etc. and melted to obtain molten glass.

(iii) The molten glass is refined and then formed into a glass platehaving a prescribed thickness by e.g. a float process.

(iv) The glass plate is annealed and then cut into a prescribed size toobtain a colored glass plate of the present invention.

(v) As the case requires, the cut glass plate may be subjected totempering treatment, may be processed into laminated glass, or may beprocessed into double-layered glass.

The glass matrix composition raw materials may be ones commonly used asraw materials for usual soda lime silica glass, such as silica sand, analumina source, a magnesia source, a calcia source, an alkali oxidesource, etc.

The iron source may, for example, be iron powder, iron oxide powder,rouge, etc.

The titanium source may, for example, be titanium oxide, etc.

The vanadium source may, for example, be vanadium oxide, etc.

The oxidizing agent may, for example, be sodium nitrate, etc. Theoxidizing agent is one to accelerate oxidation of iron in molten glass.

The reducing agent may, for example, be carbon, coke, etc. The reducingagent is one to prevent oxidation of iron in molten glass.

Further, SnO₂ may be used as a reducing agent or a fining agent, and SO₃may be used as an oxidizing agent or a fining agent.

In the colored glass plate of the present invention as described above,as represented by mass percentage based on oxide, total iron calculatedas Fe₂O₃ is from 0.3 to 1.2%, total titanium calculated as TiO₂ is from0.2 to 1.1% and total vanadium calculated as V₂O₅ is from 0.02 to 0.3%,whereby despite containing substantially no expensive cerium or othercolorant components, it satisfies Te≦55% (as calculated in a thicknessof 4 mm), Tv≧70% (as calculated in a thickness of 4 mm) and Tuv≦12% (ascalculated in a thickness of 4 mm), while transmitted light has a greencolor tone.

EXAMPLES

Now, the present invention will be described specifically with referenceto Examples, but it should be understood that the present invention isby no means limited to such Examples.

Ex. 1 to 8 are Examples of the present invention, and Ex. 9 is aComparative Example.

(Te)

With respect to an obtained glass plate, the solar transmittance (Te) asstipulated in JIS R3106 was obtained as a value calculated in athickness of 4 mm.

(Tv)

With respect to an obtained glass plate, the visible light transmittance(Tv) (illuminant A, 2 degrees field of vision) as stipulated in JISR3106 was obtained as a value calculated in a thickness of 4 mm.

(Tuv)

With respect to an obtained glass plate, the UV transmittance (Tuv) asstipulated in ISO-9050 was obtained as a value calculated in a thicknessof 4 mm.

(Dw)

With respect to an obtained glass plate, the dominant wavelength (Dw) oftransmitted light as stipulated in JIS Z8701 (1982) was obtained.

[Ex. 1 to 9]

The respective raw materials were mixed to attain the composition shownin Table 1, and further, in Examples 1 to 7, Na₂SO₄ was mixed as anoxidizing agent in the amount shown in Table 1 as calculated as SO₃,further in Ex. 1 to 3, NaNO₃ was mixed as an oxidizing agent in theamount shown in Table 1 as calculated as NO₃, and further, in Ex. 9,coke was mixed as a reducing agent in the amount shown in Table 1, toprepare a glass raw material. The glass raw material was put in acrucible and heated to 1,500° C. in an electric furnace to obtain moltenglass. The molten glass was cast on a carbon plate and cooled. Bothsides were polished to obtain a glass plate having a thickness of 4 mm.With respect to the obtained glass plate, the transmittances weremeasured for every 1 nm by means of a spectrophotometer (Lambda 950,manufactured by Perkin Elmer) to obtain Te, Tv, Tuv and Dw. The resultsare shown in Table 1.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9Composition SiO₂ 68.1 68.1 68.1 71.3 71.2 71.3 71.5 71.6 71.8 (%) Al₂O₃1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9 1.9 MgO 3.6 3.6 3.5 3.7 3.7 3.7 3.7 3.73.8 CaO 7.6 7.6 7.6 8.0 7.9 8.0 8.0 8.0 8.0 Na₂O 12.3 12.3 12.3 12.912.9 12.9 12.9 13.0 13.0 K₂O 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Fe₂O₃0.67 0.82 0.66 0.66 0.65 0.66 0.61 0.61 0.54 TiO₂ 0.58 0.58 0.77 1.011.01 0.81 0.81 0.81 0.41 V₂O₅ 0.10 0.07 0.09 0.09 0.09 0.11 0.12 0.12 0CeO₂ 0 0 0 0 0 0 0 0 0 CoO 0 0 0 0 0 0 0 0 0 Cr₂O₃ 0 0 0 0 0 0 0 0 0 MnO0 0 0 0 0 0 0 0 0 Oxidizing SO₃ 0.1 0.1 0.1 0.1 0.3 0.3 0.1 agent (%)NO₃ 4.8 4.8 4.8 Reducing Coke 0.3 agent (%) Tv (%/4 mmt) 71.0 70.6 74.170.1 73.9 73.4 71.8 70.6 72.0 Te (%/4 mmt) 47.5 46.0 53.0 45.6 52.4 52.449.8 47.3 39.8 Tuv (%/4 mmt) 9.8 8.9 9.6 10.0 9.7 9.3 9.8 10.1 30.9 Dw(nm) 552 554 558 556 559 558 555 554 494

The colored glass plate of the present invention in each of Ex. 1 to 8satisfied Te≦55% (as calculated in a thickness of 4 mm), Tv≧70% (ascalculated in a thickness of 4 mm) and Tuv≦12% (as calculated in athickness of 4 mm), while transmitted light had a green color tone withits dominant wavelength being within a range of from 540 to 570 nm.

The colored glass plate in Ex. 9 contained no V₂O₅, whereby Tuv washigh.

Industrial Applicability

The colored glass plate of the present invention is useful as a glassplate for vehicles and buildings, and is particularly suitable as aglass plate for automobiles.

This application is a continuation of PCT Application No.PCT/JP2013/051656, filed on Jan. 25, 2013, which is based upon andclaims the benefit of priority from Japanese Patent Application No.2012-015560 filed on Jan. 27, 2012. The contents of those applicationsare incorporated herein by reference in their entireties.

What is claimed is:
 1. A colored glass plate comprising, as representedby mass percentage based on oxides: SiO₂: from 65 to 75%, Al₂O₃: from 0to 6%, MgO: from 2 to 6%, CaO: from 5 to 15%, total iron calculated asFe₂O₃: from 0.5 to 1.2%, total titanium calculated as TiO₂: from 0.2 to1.1%, and total vanadium calculated as V₂O₅: from 0.02 to 0.3%, whereinsaid colored glass plate comprises substantially no cerium, cobalt,chromium or manganese and has: a solar transmittance as stipulated inJIS R3106 (1998) of at most 55% as a value calculated in a thickness of4 mm, a visible light transmittance (illuminant A, 2 degrees field ofvision) as stipulated in JIS R3106 (1998) of at least 70% as a valuecalculated in a thickness of 4 mm, an UV transmittance as stipulated inISO-9050 of at most 12% as a value calculated in a thickness of 4 mm,and a dominant wavelength of transmitted light as stipulated in JISZ8701 (1982) of from 540 to 570 nm.
 2. The colored glass plate accordingto claim 1, which further comprises, as represented by mass percentagebased on oxide, from 5 to 18% of Na₂O.
 3. The colored glass plateaccording to claim 1, which has a dominant wavelength of transmittedlight as stipulated in JIS Z8701 (1982) of from 552 to 556 nm.
 4. Thecolored glass plate according to claim 1, comprising, as represented bymass percentage based on oxides: SiO₂: from 68 to 73%, Al₂O₃: from 0.5to 3.5%, MgO: from 2.5 to 5%, CaO: from 6 to 11%, Na₂O+K₂O: from 10 to18%, total iron calculated as Fe₂O₃: from 0.5 to 0.9%, total titaniumcalculated as TiO₂: from 0.5 to 1.0%, and total vanadium calculated asV₂O₅: from 0.05 to 0.20%.
 5. The colored glass plate according to claim1, comprising, as represented by mass percentage based on oxides: SiO₂:from 70 to 72%, Al₂O₃: from 1.5 to 2.0%, MgO: from 3 to 4%, CaO: from 7to 9%, Na₂O+K₂O: from 11 to 16%, total iron calculated as Fe₂O₃: from0.6 to 0.7%, total titanium calculated as TiO₂: from 0.7 to 0.9%, andtotal vanadium calculated as V₂O₅: from 0.10 to 0.15%.
 6. The coloredglass plate according to claim 1, wherein the content of cerium, cobalt,chromium and manganese in the colored glass plate is less than 0.05% asrepresented by mass percentage.
 7. The method according to claim 1,wherein the content of cerium, cobalt, chromium and manganese in thecolored glass plate is less than 0.01% as represented by masspercentage.
 8. The method according to claim 1, wherein the coloredglass plate comprises no cerium, cobalt, chromium or manganese.
 9. Thecolored glass plate according to claim 1, which has a solartransmittance as stipulated in JIS R3106 (1998) of at most 50% as avalue calculated in a thickness of 4 mm, a visible light transmittance(illuminant A, 2 degrees field of vision) as stipulated in JIS R3106(1998) of at least 71.5% as a value calculated in a thickness of 4 mm,an UV transmittance as stipulated in ISO-9050 of at most 10% as a valuecalculated in a thickness of 4 mm, and a dominant wavelength oftransmitted light as stipulated in JIS Z8701 (1982) of from 550 to 560nm.
 10. The colored glass plate according to claim 9, comprising, asrepresented by mass percentage based on oxides: SiO₂: from 68 to 73%,Al₂O₃: from 0.5 to 3.5%, MgO: from 2.5 to 5%, CaO: from 6 to 11%,Na₂O+K₂O: from 10 to 18%, total iron calculated as Fe₂O₃: from 0.5 to0.9%, total titanium calculated as TiO₂: from 0.5 to 1.0%, and totalvanadium calculated as V₂O₅: from 0.05 to 0.20%.
 11. The colored glassplate according to claim 10, which has a dominant wavelength oftransmitted light as stipulated in JIS Z8701 (1982) of from 552 to 556nm.
 12. The colored glass plate according to claim 9, comprising, asrepresented by mass percentage based on oxides: SiO₂: from 70 to 72%,Al₂O₃: from 1.5 to 2.0%, MgO: from 3 to 4%, CaO: from 7 to 9%, Na₂O+K₂O:from 11 to 16%, total iron calculated as Fe₂O₃: from 0.6 to 0.7%, totaltitanium calculated as TiO₂: from 0.7 to 0.9%, and total vanadiumcalculated as V₂O₅: from 0.10 to 0.15%.
 13. The colored glass plateaccording to claim 12, which has a dominant wavelength of transmittedlight as stipulated in JIS Z8701 (1982) of from 552 to 556 nm.
 14. Thecolored glass plate according to claim 13, wherein the content ofcerium, cobalt, chromium and manganese in the colored glass plate isless than 0.05% as represented by mass percentage.
 15. The methodaccording to claim 13, wherein the content of cerium, cobalt, chromiumand manganese in the colored glass plate is less than 0.01% asrepresented by mass percentage.
 16. The method according to claim 13,wherein the colored glass plate comprises no cerium, cobalt, chromium ormanganese.
 17. A method for producing a colored glass plate, whichcomprises melting glass raw materials, followed by forming to obtain acolored glass plate comprising, as compositional components of the glassplate after the forming and as represented by mass percentage based onoxides: SiO₂: from 65 to 75%, Al₂O₃: from 0 to 6%, MgO: from 2 to 6%,CaO: from 5 to 15%, total iron calculated as Fe₂O₃: from 0.5 to 1.2%,total titanium calculated as TiO₂: from 0.2 to 1.1%, and total vanadiumcalculated as V₂O₅: from 0.02 to 0.3%, wherein said colored glass platecomprises substantially no cerium, cobalt, chromium or manganese andhas: a solar transmittance as stipulated in JIS R3106 (1998) of at most55% as a value calculated in a thickness of 4 mm, a visible lighttransmittance (illuminant A, 2 degrees field of vision) as stipulated inJIS R3106 (1998) of at least 70% as a value calculated in a thickness of4 mm, an UV transmittance as stipulated in ISO-9050 of at most 12% as avalue calculated in a thickness of 4 mm, and a dominant wavelength oftransmitted light as stipulated in JIS Z8701 (1982) of from 540 to 570nm.
 18. The method for producing a colored glass plate according toclaim 17, wherein the glass plate further contains, as its compositionalcomponent and as represented by mass percentage based on oxide, from 5to 18% of Na₂O.
 19. The method for producing a colored glass plateaccording to claim 17, wherein the colored glass plate has a solartransmittance as stipulated in JIS R3106 (1998) of at most 50% as avalue calculated in a thickness of 4 mm, a visible light transmittance(illuminant A, 2 degrees field of vision) as stipulated in JIS R3106(1998) of at least 71.5% as a value calculated in a thickness of 4 mm,an UV transmittance as stipulated in ISO-9050 of at most 10% as a valuecalculated in a thickness of 4 mm, and a dominant wavelength oftransmitted light as stipulated in JIS Z8701 (1982) of from 550 to 560nm.